Mudslides could be predicted with acoustic sensors

THEY were warned. Heavy rainfall has been blamed for the largest landslide in the US for a decade. On Monday, the government said the area was considered safe, but it has emerged that the potential for a catastrophic slide was predicted 15 years ago.

By Tuesday, the slide in Oso, Washington state, had killed 14 people, with 176 still missing. Covering about 2.5 square kilometres, it occurred at 10.45 am local time on 22 March, leaving much of the town under mud and debris up to 12 metres thick.

After viewing images of the scene, geologist and landslide expert Dave Petley at Durham University, UK, speculates that heavy rain in March saturated soil on the upper slope, causing it to fail and slide onto lower slopes. As the load squashed the lower reaches, it liquefied the soil, creating a muddy torrent.

A 1999 report from the US Army Corps of Engineers warned of the potential for a deadly slide at Oso, but the Department of Emergency Management said on Monday that the area was considered safe.

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